Embraer and GE recently held a series of test flights in an E170. The tests, flown out of Embraer’s Gavião Peixoto facilities, benchmarked the operational characteristics of the airplane and its GE CF34-8E engines when powered by HEFA (hydro-processed esters and fatty acids) fuel under a broad range of unique flight conditions. The flights involved powering one of the two GE engines with the maximum ASTM permissible mix of 50 percent jet-A and HEFA derived from camelina. Commonly known as wild flax, camelina grows wild in Northern Europe and Central Asia; it was introduced recently in the U.S. as a cattle and chicken feed supplement.

“HEFA fuel is a sustainable alternative fuel option, meaning this type of synthetic fuel is produced from renewable feedstocks that also reduce total greenhouse gas emissions. It has demonstrated its ability to be a possible alternative fuel for aviation use. It should be pointed out that it is not the only sustainable alternative fuel option as there are multiple alternative fuel offerings that have the potential to be used in aviation, but this is definitely a good, viable option,” Mike Epstein, leader of alternative fuels for GE Aviation, told AIN.

According to Epstein, a practical application for HEFA fuel will not be available in the short term. “Sasol in South Africa is already using an alternative blend of jet fuel for commercial aircraft. For alternative fuels to see more widespread use, refineries dedicated to alternative fuels will need to be built to produce the quantities of fuel required. At this point we are five to ten years away from that happening, but in the next few years we’ll likely see an increase in alternative blends of fuel used in both commercial and military aircraft,” he said.  

For the consumer one of the big questions is cost, which Epstein said is highly site- and region-dependent, but time will help. “Our expectation is that in a few areas, taking into account existing government incentives, cost parity may be reached in the short term. In the long run technologies will continue to be developed and matured that will allow for reduced costs and more widespread production and utilization,” he said.

In Epstein’s opinion the biggest task will be building the refineries to produce the fuel as they will require significant capital investment. The good news for the operator is the fuel will be “drop-in,” meaning no changes will be required of engine or aircraft technology to use it.

Over time alternative fuels could replace jet fuel completely, but Epstein cautioned it will be a gradual process. The fuel will initially be a blend of alternative fuel and jet-A and then slowly progress to 100 percent alternative fuels.

“There are challenges such as [energy] density that remain with respect to 100-percent alternative fuels, but a lot of good companies are working on those challenges and we are probably several years away from 100-percent alternative fuel blends being ready for testing,” he said.